This invention relates to apparatus for compaction such as for example tamping ground over excavations and more particularly to compaction apparatus and method usable with backhoes.
One class of equipment for tamping earth includes an excavation vehicle carrying a backhoe or the like that articulates a weight. It raises and drops the weight and thus tamps earth down or breaks objects beneath it. This class of compaction or crushing equipment includes a frame with a weight mounted within it and hydraulic cylinders that provide power to lift the weight and permit it to drop. For this purpose, the weight is connected by an elongated member such as a cable to the piston of the hydraulic cylinder. The elongated member is wound over pulleys to provide increased distance of movement as compared to the distance of movement of the piston, and to cause the elongated member to be above the impact area for the weight. The end of the cable is attached to the weight to lift the weight and permit it to drop as the piston is articulated by the hydraulic cylinder. Typically, the excavation vehicle and backhoe are used for other purposes and the compaction apparatus is an attachment.
In one type of prior art compaction apparatus in this class, the pulleys are mounted at stationary locations on the frame so that the movement of the piston pulls the cable over pulleys that rotate but does not move the pulleys with respect to the frame of the compaction or crushing apparatus. This type of tamping apparatus has a disadvantage in that the momentum of the weight hitting the impact surface is reduced excessively by frictional resistance, particularly from the cable pulley wheels and piston of the hydraulic cylinder.